The splitting of water into hydrogen is crucial because of its potential use in chemical industries and in energy applications. In our lab, we have designed a catalyst composed of ternary interstitial cobalt molybdenum phosphide (CoMoP2) that allows efficient hydrogen evolution in acidic environment. In this work, we report the mechanistic study of CoMoP2 under functional conditions, using in situ differential X-ray absorption (△μ) spectroscopy. We probed the local and electronic structures of both the molybdenum and cobalt elements for the as prepared material as well as the precatalytic and catalytic states. The as prepared material showed a typical CoMoP2 hexagonal structure. Charge transfer from cobalt to adsorbate occurred under functional conditions (pH = 1) at open circuit potential (+0.2 V vs RHE). In its electrocatalytic state (overpotential η = 500 mV), the terminal Co-P site is found to be the active site and shows spectroscopic features that indicate the presence of surface terminal Co(H2O)-P-H units.

Differential electrochemical x-ray absorption spectroscopy of hydrogen evolution electrocatalysis on metal phosphides

253rd National Meeting (2017)

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